The present invention relates to caging systems for housing and isolating laboratory animals including food and water feeders to feed such animals and, in particular, to an improved food and water dispenser that can be supported by an edge of the case and an improved cage assembly that can be used therewith.
In the production of colonies of rats, mice or other small laboratory animals by breeding, the mice are housed in animal cages which are arranged in close proximity within confined areas. The colonies are subject to airborne diseases which spread rapidly from one cage to another, particularly where the surrounding environment is not particularly sanitary. It is particularly desirable to maintain a closed, limited defined flora colony, that is, a colony of mice having a limited number of bacteria which are constantly the same. This is also the manner in which animals are maintained during laboratory experimental work to maintain the animals free of outside contaminants.
Conventional animal cages for maintaining animals in a reduced contamination environment are described in U.S. Pat. Nos. 4,480,587 and 4,640,228. These latter type of "shoebox" transparent cage bodies employ a detachable air filter which extends across the entire top of the lid and a retainer member which retains the filter thereagainst. However, and as particularly described in U.S. Pat. No. 4,640,228, these conventional cages employ a wire bar lid feeding and water dispenser to minimize the number of times the cage must be opened. The wire bar lid essentially consists of a stainless steel bar construction having an outer rim which is supported along the entire lip of the cage. A plurality of bars extend across the rim. The lid extends deep within the cage interior for easy access by the animal disposed therein. Within this lid is placed the food items and a water bottle. By providing a lid made of stainless steel or some other metal, the filter and plastic lid are protected from the animal.
However, this type of feeding and watering structure has been less than satisfactory for the following reasons. First, the downwardly sloping surface of the structure typically extends deep within the middle of the cage assembly. Accordingly, it has been found that larger laboratory animals have great difficulty in moving about the cage since the lid extends substantially within the cage interior. Accordingly, as the laboratory animal increases in size, the area within the cage assembly that the laboratory animal is able to move is severely diminished. Secondly, the aforementioned cage construction requires a handler to physically remove the feeding dispenser in order to gain access to the interior of the cage and laboratory animal contained therein. Thirdly, the aforementioned structure limits the visibility of the laboratory animal contained in the cage. When viewing the laboratory animal from the top, the additional opaqueness of the water bottle and food items further hinders the view of the laboratory animal. When viewing an animal from a cage end, the food carrying portion of the lid blocks the view of animals positioned at the opposite end of the cage.
Accordingly, it is desired to provide an improved water bottle holder and feeder construction that permits increased mobility of the laboratory animal contained within the cage assembly and improve visibility of the laboratory animal contained therein. It is also desired to provide an improved cage construction that protects the integrity of the reusable filter once protected by the aforementioned lid construction. The invention disclosed herein provides a wire bar cover in the body portion and provides for such an improved cage assembly construction.